Roll die

ABSTRACT

A roll die for use with a thread roiling apparatus for roll forming threads on a part is disclosed. The roll die generally comprises a stationary roll die having a first predetermined thread on one surface thereof. The roll die also comprises a moving roll die having a second predetermined thread on a first predetermined portion of a surface thereof and a third predetermined thread on a second predetermined portion of the surface of the moving roll die. The moving roll die also includes at least one ramp arranged between a second predetermined thread and a third predetermined thread. The roll die may be capable of roll forming multiple threads on a fastener or threaded blank or part in a single pass.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a roll die, and moreparticularly relates to a flat roll die for use in a thread roller forrolling threads on a fastener or other threaded part.

2. Description of Related Art

Thread rolling machines have been known for many years in the art. Someprior art thread rolling machines have a movable die that isreciprocated back and forth relative to a stationary die in order toform threads on the shanks of fasteners or blanks Which are fed one at atime between the dies. Generally, the blanks are stored in a supplyhopper and are fed from the hopper to the dies along a track defined bya pair of parallel rails. The blanks are held in the track. by an upperhold down rail based above the parallel rails. Generally, in each blankenters an injection position adjacent to the dies and a pressure orfinger feeds the blank between the dies. Many of these thread rollingmachines of the prior art are capable of forming threads of manydifferent types and sizes on blanks. When the blank or work piece isplaced between the dies the stroke of the reciprocating and movable diemay allow for the work piece or part to be rolled along the die facesand the work piece material is displaced to form the required threadthereon.

Some prior art thread rolling machines are also capable of roll formingmultiple threads on a fastener or threaded part. Generally, this takesmultiple passes to have multiple threads arranged on the threaded part.The prior art also has thread roll forming machines that are capable ofrolling multiple threads On a fastener but have to use multiple pieceroll dies in order to create the multiple threads on a threaded part orfastener. Hence, the die change over to replace the die to a second dieor to have more than one die arranged in the machine increases the costand time necessary to manufacture multi-threaded fasteners. Therefore,there is a need in the art for an improved flat roll die that may rollform multiple threads on a fastener or threaded part in a single pass.

There also is a need in the art for a roll die, made from a single pieceof steel, that is capable of roll forming multiple threads on afastener. Furthermore, there is a need in the art for an improved rolldie that utilizes roll on and off ramps between a fine and coarse threadintersection on a single surface or face of a moving roll die. Therealso is a need in the art for an improved flat roll die that may allowfor an intersection between fine and coarse threads that may not damagethe part being rolled or cause slipping of the part due to an abruptmismatch between the overlap of two different thread types. There alsois a need in the art for a flat roll die that is capable of roll formingmultiple threads on a fastener that is more efficient and may allow forincreased manufacturing capacities with less down time of the machineryat a lower cost.

SUMMARY OF THE INVENTION

One object of the present invention may be to provide an Unproved flatroll die.

Another object of the present invention may be to provide a roll diethat is capable of roll forming multiple threads on a fastener orthreaded part in a single pass through the die.

Still another object of the present invention may he to provide a rolldie that is designed front a single piece of material, such as steel.

Still another object of the present invention may be to provide a rolldie that utilizes roll on and off ramps between a fine and coarse threadintersection on a surface or face of the roll die.

Still another object of the present invention may be to provide a rolldie that allows for an intersection between a fine and a coarse threadthat may not damage the part being rolled.

Still another object of the present invention may be to provide a rolldie that does not cause slipping of the part due to an abrupt mismatchbetween the overlap of two different size threads.

Still another object of the present invention may be to provide a rolldie that increases efficiency and reduces down time of the machinerythus reducing costs and increasing profit for the manufacturer.

According to the present invention, the foregoing and other objects andadvantages are obtained by a novel design for a roll die. The roll die,which is for use in a thread rolling apparatus for roll forming threadson a part, comprises a stationary roll die having a first predeterminedthread on a surface thereof. The roll die further comprises a movingroll die having a second predetermined thread on a first predeterminedportion of the surface thereof and a third predetermined thread on asecond predetermined portion of the surface of the moving roll die. Theroll die also comprises at least one ramp arranged between a secondpredetermined thread and a third predetermined thread on the moving rolldie. A single roll die may allow for roll forming of multiple threads ona fastener or threaded part in a single pass.

One advantage of the present invention may be that it provides animproved flat roll die.

A further advantage of the present invention may be that it provides fora roll die apparatus that may roll form multiple threads on a fastenerin a single pass.

Still a further advantage of the present invention may be that itprovides for a roll die that is designed from a single piece ofmaterial, such as but not limited to a steel.

Still another advantage of the present invention may be that it providesa roll die that utilizes roll on and off ramps between first and secondthread intersections.

Still another advantage of the present invention may be that it providesfor a roll die that allows an intersection between a fine and a coarsethread to not damage the part being rolled therebetween.

Still another advantage of the present invention may be that it providesfor a roll die that does not generally allowing slipping of a part beingrolled due to an abrupt mismatch between the overlap of two differentthreads therebetween.

Yet another advantage of the present invention may be that it providesfor a roll die that reduces the cost while, increasing the efficiency ofthreading multiple threads on a fastener in a roll die thread rollerapparatus or machine.

Yet another advantage of the present invention may be that it providesfor a roll die that may increase the number of parts being manufacturedin a predetermined time frame compared to parts being manufactured by aprior art roll die in the same time frame.

Other objects, features and advantages of the present invention maybecome apparent from the subsequent description and appended claims,taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side view of a stationary die according to the presentinvention.

FIG. 2 shows a side view of a moving die according to the presentinvention.

FIG. 3 shows a close up of an intersection between a first and secondthread of a moving die according to the present invention.

FIG. 4 shows a top view of a moving die according to the presentinvention.

FIG. 5 shows a flat die thread roller machine having a roll dieaccording to the present invention installed therein.

FIG. 6 shows a blank and dual threaded fastener according to the presentinvention.

BRIEF DESCRIPTION OF THE EMBODIMENTS

Referring to the drawings, there is shown a roll die 10 according to anembodiment of the present invention. Generally, the present invention isa roll die 10 that is a flat roll die that may roll form multiplethreads on a fastener, blank or threaded part in a single pass. Theprior art roll dies generally had to use multiple passes to roll formmultiple threads on a fastener or threaded. part and also had to usemultiple piece roll dies to perform such multi thread rolling. The rolldie 10 of the present invention is a die that is designed from a singlepiece of material. In one contemplated embodiment the material is asteel, however any other metal, ceramic, plastic, composite or naturalmaterial may also be used to form the roll die 10 of the presentinvention. The roll die 10 of the present invention may utilize in itssingle piece construction roll on and off ramps 12 between a fine 14 andcoarse thread 15 intersection. These ramps 12 may allow theintersections between the fine 14 and coarse threads 16 to not damagethe part being rolled form therebetween or cause slipping of the partdue to an abrupt mismatch between the overlap 12 of the two differentthread sizes.

Generally, the roll die 10 of the present invention is a flat roll die10. However, it is also contemplated that it may he used on a rotary diewhich is used in conjunction with a stationary shoe or any other type ofdie known to be capable of roll forming threads onto a fastener, blankor part. Generally, the roll die 10 of the present invention. may useany known thread combination specified by the customer. Generally, thethread form is designed. and tailored to the multi thread. fastener orpart being manufactured by the customer. Hence, the thread form may bespecified in inch series or metric series and may be tailored anddesigned by using key properties of the part being roiled. Some of theseproperties are as follows, the blank diameter, the pitch diameter themajor diameter, the root radii, the crest radii, and the flank anglesare all properties that may be used when designing thread forms for aflat roll die 10 according to the present invention. It should furtherbe noted that the roll die 10 of the present invention may also usecustom tailored helix angles when creating the multi thread roll dies10. The helix angles generally are calculated by using customer providedinformation, such as the pitch diameter, the thread form depth, the rootradii depth, the crest radii, and the major diameter of the finishedrolled part. All of these calculations may he used in determining thehelix intervals required of the multi thread roll dies 10 of the presentinvention, It should further be noted that the helix angle may beverified and inspected on the die faces with a helix angle inspectionplate.

Generally, the flat roll die 10 of the present invention may be used inany known fiat die thread roller machine 18 in the prior art. Onecontemplated thread roller 18 for use with the present invention mayinclude a feed hopper that orients and feeds blanks or work pieces 20into a feed chute 22 and then a pressure injector 24 which is operatingin a timed relationship to the moving the 26, may inject, a blank orwork piece 20 between the dies at the start end of the moving die 26. Inthe roll die 10, the threads are rolled onto the blank 20 by moving orreciprocating, the moving the 26 with relation to a stationary roll die28. The roll forming machine 18 generally has a base or body member 17upon which is mounted a flat base plate. Generally, the stationary rolldie 28 of the present invention is supported and fixed in positionrelative to the base plate, while the movable or reciprocating die 26 issupported for a back and forth reciprocation or notion relative, to thestationary die 28 by a guide shoe, which is mounted on the base platewhich receives a sliding die holder therein. A feeder system may feedthe blanks 20 to the start edge of the moving die 26 and stationary die28 and may allow for the blank 20 to be passed through the moving roddie 26 and stationary die 28 in a single path, thus rolling, a multithread configuration onto the blank 20 at the desired configurationrequested by the customer. It should be noted that any other type orsetup of a flat die thread roller machine 18 may be used, not just thatone described herein.

The flat roll die 10 of the present invention generally includes astationary roll die 10 and a moving or reciprocating roll die 26arranger adjacent to one another with a predetermined distance arrangedtherebetween. The distance arranged therebetween may be capable of beingadjusted based on the diameter of the blank 20 being rolledtherethrough. Generally, the stationary roll die 28 may be made of asteel material, however any other metal, ceramic, composite, or naturalmaterial may be used for the stationary roll die 28. The stationary rolldie 28 generally may have a rectangular shape when viewed from a topsurface thereof. The stationary roll die 28 may be manufactured via anyknown manufacturing technique, such as but not limited to grinding,milling, electrical discharge machine, etc. In one contemplatedembodiment the stationary roll die 28 may be manufactured with onlycoarse threads 16. It should be noted that the coarse thread 16 is putonto the stationary die 28 using properties that pertain to its form andfunction. Furthermore, the coarse threads 16 are put onto the stationarydie 28 using a central location wherein the central location is verifiedby using a helix inspection gage. The central location of the coarsethreads 16 is crucial in form and function between, the moving die 26and the stationary die 28. The central location generally is a centerpoint or a mid. point of the die face 30 having the threads 16 thereon.The center point 32 may allow for the stationary die 28 to be flipped inthe shoe holding the stationary die 28 in the thread rolling machine 18and still allow for threads 16 to be rolled onto a blank 20 in theproper orientation to the blank 20 being rolled. Hence, the center ormid point 30 of the stationary die 28 is identified and the threads 16are manufactured onto the face 30 about or around the center point 32 toallow for proper alignment of the coarse threads 16 on the stationaryroll die 28. It should be noted that any type of thread, such as anycoarse threads 16, any fine threads 14, or any extra fine threads may beused on the stationary die 28 of the present invention. Generally,coarse threads 16 are defined as any type of thread that has betweeneight and sixty four threads per inch depending on the major diameter ofthe blank 20 being used. A fine thread 14 is generally defined as anytype of thread having between twelve and eighty threads per inchdepending on the major diameter of the blank 20 being used. Furthermore,extra fine thread is generally defined as having between twenty andthirty two threads per inch depending on the major. diameter of theblank 20 being used. Therefore, in the present invention generally acoarse thread 16 is the only thread arranged on the working face 30 ofthe stationary roll die 28. It should be noted that both ends of thestationary die 28 also may include angled surfaces 40 to allow foradjustments of the stationary die 28 with relation to the base 17 of theroll thread roller machine 18. This may allow for inserts or shims to beplaced therein thus allowing the stationary roll die face 30 to be at aproper position with relation to the blank 20 being rolled and themoving roll die 26 of the present invention. Therefore, an type ofstationary die 28 using any of the parameters as discussed above andusing any type of coarse thread 16 using the parameters discussed abovemay be placed and arranged on the face 30 of the stationary roll die 28.It should be noted that coarse threads 16 may be arranged on the face 30parallel to one another and set at a predetermined angle on the face 30.

The roll die 18 of the present also includes a moving or reciprocatingroll die 26 that is designed to place multiple threads on a blank 20being rolled thereon. The moving roll die 26 may be manufactured throughany known technique, such as but not limited to grinding, milling,electrical discharge machine, or any other type of manufacturingtechnique capable of placing the threads 14 on the working die face 34of the moving roll die 26. Generally, the moving roll die 26 is alsomade of a steel material, however any other metal, ceramic, plastic,composite, or natural material may also be used for the moving roll die26. The moving rolling die 26 of the present invention generally ismanufactured with both coarse 16 and fine threads 14 on the die face 34.The orientation of the fine 14 and coarse threads 16 is crucial indeciding the form and function of the finished rolled pan. Generally, ahelix angle of both coarse 16 and fine thread 14 are calculated usinginformation received from the customer. This information generallyincludes, but is not limited, to, the pitch diameter, the thread formdepth, the root radii, the crest radii, and the major diameter of thefinished rolled part. Generally, both the moving die 26 and thestationary die 28 may or may not have a starting end 36 and a finishing,end 38, The start end 36 of the moving roll die 26 generally utilizesthe coarse thread 16 only. This coarse thread 16 may extend apredetermined distance towards the opposite end or finishing end 38 ofthe moving roll die 26. The coarse thread 18 arranged at the start end36 of the moving roll die 26 may have a predetermined length. Thislength may generally he calculated using the following formula: blankdiameter×(Pi)×(2.75) will equal the length of the coarse thread 16 startportion of the moving die 26. It should further be noted that thiscoarse thread 16 may also be centralized in accordance to the helicalangle of the coarse thread 16 on the stationary roll die 28. This mayallow for the centralization of the coarse thread 16 on the moving die26 to match the centralization of the coarse thread 16 on the stationaryroll die 28. The same type of centralization calculation may beperformed as described above wherein the mid point of the moving rolldie 26 or the mid point of the coarse threads 16 of the moving roll die26 may be identified and the coarse threads 16 manufactured onto theworking face 34 of the moving roll die 26, based on the central or midpoint location on the die face 34. This may allow for the moving die 26to he flipped over and still apply the coarse threads 16 in unison withthe coarse threads 16 on the stationary die 26.

The other portion of the working face 34 of the moving roll die 26 mayhave a fine thread 14 arranged thereon. The length of the fine thread 14on the moving roll die 26 may be dedicated to the remaining amount ofmoving roll die face 34 not occupied by the coarse threads 16. Hence,whatever has not been formed with coarse threads 16 may be formed withthe fine threads 14 according to the present invention. However, itShould be noted that any other type of relationship between the coarsethreads 16 and fine threads 14 may also occur other than just the coarsethreads 16 being followed by fine threads 14, such as but not limited tocoarse threads 16 followed by fine threads 14 followed by coarse threads16, etc. It should further be noted that the coarse threads 16 on themoving die 26 and the coarse threads 16 on the stationary die 28 may ormay not be the same. The relationship between the fine 14 and coarsethreads 16 is crucial to the ability to have multi threads rolled ontothe blank 20. It should be noted that the fine thread 14 must also becentralized to the coarse thread 16 in a general relationship of pitchto pitch function. Furthermore, the coarse 16 and fine threads 14 musthave radii depths that have the exact same depth planes because failureto achieve this exact same depth plane may cause a pitch diameter underor oversized failure in the fine thread 14 with relation to the coarsethread 16 on the finished roiled part. It should further be noted thatthe crest radii depth between the coarse 16 and fine 14 thread may havea different plane depth due to the difference in the pitch diameters ofthe fine 14 and coarse threads 16. Furthermore, the fine 14 and coarsethreads 16 have an overlap at a predetermined area wherein the overlaphaving a predetermined length that is determined through overlap of boththe fine 14 and coarse threads 16 having different helical angles. Thisoverlap is adjustable through pullout of the tool being used for thethread manufacturing. It should he noted that this overlap length iscrucial as the overlap may dictate the length of the On ramp and offramps 12 which create the transition from the fine 14 to coarse threads16 on the moving roll die 26. It should be noted that the length of theoverlap may be calculated to let the root radii of the fine 14 andcoarse thread 16 to overlap each other such that no voids occur betweeneach root radius. Therefore, it should be noted that generally at leastone ramp 12 is arranged between each of the fine 14 and coarse threads16. In one contemplated embodiment the ramp 12 is located between eachgenerally parallel but offset fine 14 and coarse thread 16. It should benoted that the ramp 12 generally may be made in either a radial or flatstyle or shape. The ramp 12 may allow for an easy transition between thefine 14 and coarse threads 16 for the part being rolled. It shouldfurther be noted that the ramp length on both the fine 14 and coarsethreads 16 may be calculated using the blank diameter and the pitchdiameter. The ramps 12 on the fine 14 and coarse threads 16 generallyare ground, milled or for formed with an electrical discharge machine,such as that found in a five axis machine. It should be noted that theramps 12 may have any known width and angle or ascent or decent fromeither the fine thread 14 or the coarse thread 16 on the working face 34of the moving die 26.

It should be noted that the fine thread 14 form may be specified by thecustomer and that the form depth and helix angle are all calculatedaccording to the pitch diameter needed and diameter of the part beingrolled. The same may apply for the coarse thread 16 and may be any formas specified by a customer. In one contemplated embodiment, the coarsethread 16 may be offset a predetermined distance from the fine thread 14on the face 34 of the moving die 26. This may allow the fine thread 14to align with and create a fine thread on the crest of the coarse threadof the blank 20. This may allow a power nut to be arranged over thecoarse thread portion of a multi-thread bolt and a lock not to bearranged and interact with a fine thread portion of a multi thread bolt,thus allowing for a mechanically locked bolt and nut apparatus.

It should also be noted that the stationary die 28 and moving die 26 mayhave any known length, width, and thickness. In one contemplatedembodiment, each of the dies have a length of approximately seveninches, a width of approximately three inches and a depth ofapproximately one and a half inches. However, any other known dimensionsmay be used for both the moving die 26 and the stationary die 28. Itshould also be noted that it is also contemplated to use a ramp 12 atboth the start end 36 and the finish end 38 of the stationary die 28 andthe moving die 26. it is also contemplated to use the angled surfaces 40on each end of the moving die 26, such as those described above for thestationary die 28. These angled surfaces 40 on the end may help toproperly align both the moving die 26 and the stationary die 28 withrelation to the blank or part 20 being passed therethrough.

In operation, the roll die 10 of the present invention may be mounted asa single piece flat roll die 10 to a thread rolling machine 18. The part20 may be inserted into the flat toll die 10 between a stationary die 28and a moving die 20, which moves and reciprocates with relation to thestationary die 28 thus roll forming multiple threads into the part 20 ina single pass through the flat roll die 10. The moving die 26 may thenreturn back to its starting position and the next blank or part 20 to bethreaded may be arranged therebetween and the process will repeat withthe moving roll die 26 moving in a linear direction with relation to thestationary die 28, rolling the blank 20 along the threads of both thestationary die 28 and the moving die 26, thus roll forming threadshaving a predetermined parameters as discussed above onto the blank 20.The resulting dual threaded fasteners 42 may be capable of being usedwith a coarse nut and/or a fine nut to create a mechanically locked boltand nut assembly that is resistant to loosening from vibration. Theblanks 20 generally are fed from a storage hopper along a transfer lineto a position where the blank 20 contacts both the start end of thestationary die 28 and the start end of the moving die 26. It should benoted that any other known rolling technique, such as those describedabove, may also be used in conjunction with the moving die 26 andstationary die 28 as described herein. It should further be noted thatany combination of threads may be used on the moving die 26 or any typeof thread may be also be used on the stationary die 28.

The present invention has been described in an illustrative manner. Itis to be understood that the terminology which has been used is intendedto he in a nature of words of description. rather than that oflimitation.

Many modifications and variations of the present invention are possiblein light of the above teachings. Therefore, within the scope of theappended claims, the present invention may be practiced otherwise thanas specifically described.

What is claimed is:
 1. A roll die for use with a thread rollingapparatus for roll forming threads or a part, said roll die comprising:a stationary roll die having first predetermined threads on one surfacethereof; a moving roll die having second predetermined threads on afirst predetermined portion of a surface thereof; said moving roll diehaving third predetermined threads on a second predetermined portion ofsaid surface of said moving roll die; and at least one ramp arrangedbetween one of said second predetermined threads and one of said thirdpredetermined threads.
 2. The roll die of claim 1 wherein saidstationary roll die and said moving roll die are flat roll dies.
 3. Theroll die of claim 1 Wherein said first predetermined threads are acoarse thread.
 4. The roll die of claim 1 wherein said secondpredetermined threads are a coarse thread.
 5. The roll die of claim 1Wherein said third predetermined threads are a fine thread.
 6. The rolldie of claim 1 Wherein at least one ramp is generally radial of flat inshape, said ramp having a predetermined length.
 7. The roll die of claim1 further comprising a plurality of ramps.
 8. The roll die of claim 1wherein said first predetermined threads are arranged on said surfaceabout a central location.
 9. The roll die of claim 1 wherein said thirdpredetermined threads are offset from said second predetermined threads.10. The roll die of claim 7 wherein said offset aligns said thirdpredetermined threads with a root of said second predetermined threads.11. The roll die of claim 7 wherein said first predetermined threads arethe same as said second predetermined threads.
 12. A thread rollingapparatus for roiling threads on a fastener, said thread rollingapparatus comprising; a body; a die carrier secured to said body; areciprocal slide mounted to said body; a stationary die having firstpredetermined threads on a surface thereof, said stationary die securedto said die carrier; a moving die having second predetermined threadsand third predetermined threads on different portions of a surfacethereof, said moving die secured to said reciprocal slide; and at leastone ramp arranged between one of said second predetermined threads andone of said third predetermined threads.
 13. A method of rolling threadson a part with a thread rolling machine, said method comprising thesteps of: mounting.; a single piece flat roll die to the thread rollingmachine: inserting the part into said flat roll die; and roll formingmultiple threads on the part in a single pass through said flat rolldie.
 14. The method of claim 13 wherein said flat roll die having astationary roll die and a moving roll die.
 15. The method of claim 14wherein said stationary roll die having a coarse thread on a surfacethereof.
 16. The method of claim 15 wherein said moving roll die havingsaid coarse thread on a surface thereof and a fine thread on saidsurface thereof.
 17. A method of claim 16 wherein said moving roll diehaving at least one ramp arranged between said fine thread and saidcoarse thread.
 18. The method of claim 17 wherein said at least one rampfurther comprising a roll on and off ramp between said fine and saidcoarse thread intersections.
 19. The method of claim 13 wherein saidflat roll die having a thread with a predetermined helix angle thereon.20. The method of claim 18 wherein said roll on and off ramp have apredetermined length and generally a radial or flat shape.